Apparatus for feeding sheets

ABSTRACT

Sheets are fed one by one from the base of a stack by a reciprocating pusher carrying sheet engaging claws. The pusher is disposed within a casing closed at the front, sides, and bottom, and connected to a source of vacuum. Spaced parallel bars which support the stack span the casing from front to rear between front and rear stack stops. The claws on the pusher project upwardly between the bars. The pusher carries a closure plate which forms a displaceable back for the casing.

D United States Patent 1191 1111 3,923,297

Barny 1 1 Dec. 2, 1975 [54] APPARATUS FOR FEEDING SHEETS 3,767,186 10/1973 Shields 271/132 [75] Inventor: Jean-Jacques Barny, Lyon, France I Primary ExaminerEvon C. Blunk [73] Asslgnee: Martm samt'pnest' France Assistant ExaminerBruce H. Stoner, Jr. 22 i May 21 1974 Attorney, Agent, or FirmCamer0n, Kerkam, Sutton,

Stowell & Stowell [211 App]. No.: 471,910

57 ABSTRACT [30] Foreign Application Priority Data 1 July 31, 1973 France 73.27945 Sheets are fed one by one from the base of a stack by a reciprocating pusher carrying sheet engaging claws. 52 us. c1. 271/132 The Pusher is disposed within a Casing Closed at 51 1111.01. B6511 3/24; B65H 3/46 Sides, and bottom, and connected Source of 58 Field of Search 1. 271/132, 99, 11-15, Vacuum Spaced Parallel bars which support the stack D F span the casing from front to rear between front and rear stack stops. The claws on the pusher project up- [56] References Cited wardly between the bars. The pusher carries a closure UNITED STATES PATENTS plate which forms a displaceable back for the casing.

3,377,063 4/1968 Kirby 271/14 3 Claims, 5 Drawing Figures FIG=3 US. Patent Dec. 2, 1975 Sheet 2 of2 3,923,297

FIG-.4

2/ 7 w H\ w J 8 O u 2 3 I 9 \2 A n APPARATUS FOR FEEDING SHEETS The present invention refers to a device for the cyclic introduction of products in the form of plates into a machine for treatment and is applied more particularly by way of example to a machine for cutting and printing sheets of corrugated cardboard for the production of packing cases.

A machine of this kind known as a slotter or slotter printer comprises printing cylinders and rotary knives for rotary cutting in synchronism; the portion of the slotter known as the feeder comprises in general a pusher with claws having an alternating motion in phase with the cylinders and rotary knives in order to introduce one by one the sheets stacked in a magazine. In order that introduction of the sheets shall be done satisfactorily one by one, by each time taking solely the bottom sheet of the pack, the supporting table is furnished with front stops which leave, above the table, a free space of a height very slightly greater than the thickness of one sheet and prevent the passage of the next sheet above which might be driven forward by friction.

Such a device gives entire satisfaction when the sheets of cardboard are perfectly plane and the bottom sheet of the pack bears against the table over the whole of its surface. But it frequently happens that, as a result of defects in the manufacture proper of the corrugated cardboard, the sheets are curved like a tile so that the front edge and the rear edge of the sheet tend to lift from the supporting plate. Introduction sheet-by-sheet is then made very difficult because there is a risk of the claw on the pusher passing underneath the rear edge of the sheet without driving it forwards, and there is a risk of the front edge presenting itself above the normal passage opening and coming to a stop against the front stops. If the adjustment of the front stops or the claw on the pusher is modifiedthere would on the other hand be the risk of introducing two sheets at a time.

Devices for introduction of sheets have already been proposed in which the front edge of the sheet is flattened by pneumatic suction onto a casing actuated with an alternating motion. But in these apparatus slipping sometimes occurs and there is a risk of the sheet being introduced with a lag.

The present invention corrects these disadvantages by a device enabling profiting both by the advantages of the mechanical pusher having positive action without the possibility of slipping, and by the advantages of pneumatic suction restoring good flatness to the deformed sheets.

According to the present invention there is provided a device for the cyclic introduction of products in the form of sheets into a treatment machine, the device comprising a supporting table furnished with front and rear stops between which a stack of sheets may be located which are to be introduced one by one into the machine, a pusher with claws, means to actuate the pusher with a reciprocating motion operable on each driving stroke to drive the bottom sheet of the stack out of the stack, the supporting table comprising a casing closed at the sides and the bottom, means to couple the casing to a suction device, and spaced parallel bars extending in the direction of drive of the sheets forming the top of the table, and the pusher comprising a support bar arranged inside the casing below the bars, the claws being secured thereto, being of the same width as the space between the bars and projecting above the bars and a rear closure plate of the same transverse section as the casing constituting a displaceable rear wall in respect of the zone communicating in operation with the suction device.

In one particular embodiment of the invention, intended for products of large longitudinal dimension, the casing comprises two portions, a front portion closed at the front and sides and open towards the rear and having supporting bars fixed at the front and free at the rear, and a telescopic rear portion able to slide in the front portion and blocking the open rear of the front portion, having bars comprising a lower element movable underneath a corresponding bar of the front portion and bearing on a strut bracket resting on the bottom of the rear portion, and an upper element movable over the corresponding bar of the front portion, the pusher being displaceable within the rear portion and underneath the lower elements of the bars of the rear portion.

The invention will now be described in greater detail by referring to two particular embodiments given by way of example and illustrated in the attached drawmgs.

FIG. l is a simplified perspective with some elements cut away, of an embodiment of the feed table for a slotter of small size equipped in accordance with the invention.

FIG. 2 is a transverse section of the table along II--II in FIG. 3.

FIG. 3 is a longitudinal section along IIIIII in FIG. 2.

FIGS. 4 and 5 respectively represent, compared with FIG. 3, two conditions of a telescopic slotter for large size products.

Referring first of all to FIGS. 1 to 3, the frame 1 of the feeder has two plates 2 and 3 enclosing the usual mechanisms onto which the feed bar 4 is fixed which they actuate with an alternating to-and-fro motion. The feed table is in the form of a casing arranged between the plates 2 and 3 closed at the front by a sill S, at the rear by a crosspiece 6 and in the lower part by a plate '7. The upper portion of the casing comprises parallel and regularly spaced bars connecting the sill 5 to the rear crosspiece 6. Sheets of cardboard 11 are laid on the table, stacked between front stops l2 and rear stops 13. For simplification of FIG. 1 these rear stops 13 have not been shown there but they are seen fixed to the bars 9 in the left-hand portion of FIG. 2 and in FIG. 3.

The free space between the front stops l2 and the sill 5 is adjusted to a value very slightly greater than the thickness of a sheet ll ll, and the feeder has in the usual way driving rolls 15 which take charge of the sheet after it has passed under the stops 12.

The feed bar 4 is arranged inside the casing below the bars 9.. The driving claws 17 are fixed to the bar 4 and their width is equal to the spacing of the bars 7; thus they fill the free space between the bars and project above them. Finally, the bar 4 is furnished at the rear with a sealing plate 118 of the same transverse section as the casing.

The casing has a neck 20 through which the interior is in communication with an apparatus for putting it under vacuum such, for example, as a fan; this has not been shown in the drawings as it can be of any ordinary known type.

It can be seen that when the casing is put under vacuum the bottom sheet of the pack is flattened onto the bars 9, destroying its possible original curvature; that sheet can then be caught by the claws during the forwards motion of the pusher 4 until the sheet passes underneath the front stops 12 and reaches the driving rolls 15. It can likewise be seen that the plate 18 enables leakage of vacuum to be avoided through the rear portion of the table not covered by the sheets when these have a longitudinal dimension less than the maximum dimension. Leakages are then limited to passing through the clearance between the plate 18 and the walls of the casing.

When the transverse dimensions of the sheet are likewise less than the total width of the table leakages can likewise be reduced in the positions not covered by the sheets by removing the unnecessary claws 17 and closing the corresponding space between two bars 9 by means of a blocking plate 22. The right-hand portion of FIG. 2 thus shows two gaps between bars closed by plates 22.

The device which has just been described from FIGS. 1 to 3 presents certain disadvantages if the slotter is of large size, that is to say, if the maximum longitudinal dimension of the sheets is large. In this case the casing is of great length and the bars 9 would have to be reinforced in order not to bend under the load from the sheets increased by the effect of vacuum. In addition and above all, if one has to work with sheets of small longitudinal dimension it becomes difficult for the operator to reach the magazine for the sheets because the crosspiece 6 forms an obstacle and prevents access to the central portion of the table.

In a case like this there will preferably be used a telescopic variant upon the table casing, as shown in FIGS. 4 and 5. Here the casing 7 open towards the rear and the bars 9 are free towards the rear. A second movable casing closed at the rear by the movable crosspiece and at its lower part by the plate 26, slides in the rear opening in the front casing. The rear casing has in alignment with the bars 9 bars of two elements. The lower element 28 bears towards the front on brackets 29 forming a strut against the bottom 26. The free rear ends of the bars 9 rest on this lower element 28. The upper element 30 bears by its front portion on the corresponding bar 9. Of course the alternating motion of the feed bar 4 and the pushers 17 occurs entirely within the telescopic rear casing.

It can be seen that if one starts from the position as FIG. 4 for sheets of maximum size and pushes forwards the rear casing in order to handle smaller sheets, the bars 9 slide between the elements 28 and 30 and access to the pack of sheets 11 from the rear remains always just as easy whatever the size of the sheets. Actually the bars 28-30 can consist of a flattened tube or of the association between a flat and a U-iron, for example.

Of course the invention is not strictly limited solely to the embodiments which have just been described, but likewise covers other embodiments which would differ from them only in detail or by the employment of equivalent means.

What is claimed is:

1. A device for successively feeding the bottom sheet from a stack of sheets into a treatment machine comprising a supporting table, front and rear stops on said table between which the stack is located, a casing closed at the sides and the bottom, means for coupling said casing to a suction device, spaced parallel bars extending in the direction of feed of the sheets and forming the top of the table, a-reciprocating feeder, a transverse support bar for said feeder inside said casing and below the top bars of said casing, claws of the same width as the space between said top bars secured to said support bar and projecting upwards between and above said top bars to engage the bottom sheet at each reciprocation of said feeder, and a rear closure plate of the same transverse section as said casing, projecting under the support bar and forming a movable rear wall for said casing moving with said support bar.

2. A device according to claim 1, in which the casing comprises a front portion closed at the front and sides and open towards the rear and having supporting bars fixed at the front and free at the rear, and a telescopic rear portion able to slide in the front portion and blocking the open rear of the front portion, having bars comprising a lower element movable underneath a corresponding bar of the front portion and bearing on a strut bracket resting on the bottom of the rear portion, and an upper element movable over the corresponding bar of the front portion, the pusher being displaceable within the rear portion and underneath the lower elements of the bars of the rear portion.

3. A device according to claim 1, including removable shutters to fill the space between two adjacent bars after dismounting the claw movable therebetween, to

reduce the area of the table normally open. 

1. A device for successively feeding the bottom sheet from a stack of sheets into a treatment machine comprising a supporting table, front and rear stops on said table between which the stack is located, a casing closed at the sides and the bottom, means for coupling said casing to a suction device, spaced parallel bars extending in the direction of feed of the sheets and forming the top of the table, a reciprocating feeder, a transverse support bar for said feeder inside said casing and below the top bars of said casing, claws of the same width as the space between said top bars secured to said support bar and projecting upwards between and above said top bars to engage the bottom sheet at each reciprocation of said feeder, and a rear closure plate of the same transverse section as said casing, projecting under the support bar and forming a movable rear wall for said casing moving with said support bar.
 2. A device according to claim 1, in which the casing comprises a front portion closed at the front and sides and open towards the rear and having supporting bars fixed at the front and free at the rear, and a telescopic Rear portion able to slide in the front portion and blocking the open rear of the front portion, having bars comprising a lower element movable underneath a corresponding bar of the front portion and bearing on a strut bracket resting on the bottom of the rear portion, and an upper element movable over the corresponding bar of the front portion, the pusher being displaceable within the rear portion and underneath the lower elements of the bars of the rear portion.
 3. A device according to claim 1, including removable shutters to fill the space between two adjacent bars after dismounting the claw movable therebetween, to reduce the area of the table normally open. 